The Experts below are selected from a list of 74883 Experts worldwide ranked by ideXlab platform

Nathalie Delaunay - One of the best experts on this subject based on the ideXlab platform.

  • an attempt to characterize the human chorionic gonadotropin protein by reversed phase liquid chromatography coupled with high resolution mass spectrometry at the intact level
    Journal of Pharmaceutical and Biomedical Analysis, 2018
    Co-Authors: Julien Camperi, Audrey Combes, Jean Guibourdenche, Davy Guillarme, Valerie Pichon, Thierry Fournier, Nathalie Delaunay
    Abstract:

    Abstract For the first time, the human Chorionic Gonadotropin (hCG) hormone at the intact level was characterized by reversed phase liquid chromatography (RPLC) coupled with high resolution mass spectrometry (HRMS). This heterodimeric protein is specific to human pregnancy, consists in an α and a β subunit, so-called hCGα and hCGβ, respectively, and has 8 glycosylation sites leading to a high number of isoforMS. First, the LC method was optimized to separate the largest number of isoforMS and also to facilitate the MS Ionization process and data treatment. The initial mobile phase composition, slope of the gradient, and column temperature were appropriately selected to maximize the number of separated isoforMS. Moreover, the MS detection parameters were adjusted to i) promote the efficient transfer of the heaviest ions, ii) avoid or limit the fragmentation of the ions and iii) improve the sensitivity. The repeatability of the final method in terMS of retention times and peak areas was assessed. The method was next used to characterize two hCG-based drugs: Ovitrelle® (a recombinant hCG, r-hCG) and Pregnyl® (hCG isolated from urine of pregnant women, u-hCG). After the deconvolution step, the analytical method did not allow to observe the isoforMS of the hCGβ. This may be due to its dramatic higher heterogeneity induced by its 6 glycosylation sites and a lack of Ionization in the MS source. Nevertheless, the results revealed the presence of more than 30 hCGα isoforMS, which differ by their number and their nature in the two drugs. Then, the molecular weights of the N-glycans already described in the literature for hCG were compiled in a database to identify the hCGα glycoforMS by mass matching. This strategy was successfully applied for the identification of five glycoforMS for both r-hCG and u-hCG. This work demonstrates for the first time the potential of RPLC-HRMS for the identification of the intact hCGα glycoforMS.

Valerie Pichon - One of the best experts on this subject based on the ideXlab platform.

  • an attempt to characterize the human chorionic gonadotropin protein by reversed phase liquid chromatography coupled with high resolution mass spectrometry at the intact level
    Journal of Pharmaceutical and Biomedical Analysis, 2018
    Co-Authors: Julien Camperi, Audrey Combes, Jean Guibourdenche, Davy Guillarme, Valerie Pichon, Thierry Fournier, Nathalie Delaunay
    Abstract:

    Abstract For the first time, the human Chorionic Gonadotropin (hCG) hormone at the intact level was characterized by reversed phase liquid chromatography (RPLC) coupled with high resolution mass spectrometry (HRMS). This heterodimeric protein is specific to human pregnancy, consists in an α and a β subunit, so-called hCGα and hCGβ, respectively, and has 8 glycosylation sites leading to a high number of isoforMS. First, the LC method was optimized to separate the largest number of isoforMS and also to facilitate the MS Ionization process and data treatment. The initial mobile phase composition, slope of the gradient, and column temperature were appropriately selected to maximize the number of separated isoforMS. Moreover, the MS detection parameters were adjusted to i) promote the efficient transfer of the heaviest ions, ii) avoid or limit the fragmentation of the ions and iii) improve the sensitivity. The repeatability of the final method in terMS of retention times and peak areas was assessed. The method was next used to characterize two hCG-based drugs: Ovitrelle® (a recombinant hCG, r-hCG) and Pregnyl® (hCG isolated from urine of pregnant women, u-hCG). After the deconvolution step, the analytical method did not allow to observe the isoforMS of the hCGβ. This may be due to its dramatic higher heterogeneity induced by its 6 glycosylation sites and a lack of Ionization in the MS source. Nevertheless, the results revealed the presence of more than 30 hCGα isoforMS, which differ by their number and their nature in the two drugs. Then, the molecular weights of the N-glycans already described in the literature for hCG were compiled in a database to identify the hCGα glycoforMS by mass matching. This strategy was successfully applied for the identification of five glycoforMS for both r-hCG and u-hCG. This work demonstrates for the first time the potential of RPLC-HRMS for the identification of the intact hCGα glycoforMS.

Julien Camperi - One of the best experts on this subject based on the ideXlab platform.

  • an attempt to characterize the human chorionic gonadotropin protein by reversed phase liquid chromatography coupled with high resolution mass spectrometry at the intact level
    Journal of Pharmaceutical and Biomedical Analysis, 2018
    Co-Authors: Julien Camperi, Audrey Combes, Jean Guibourdenche, Davy Guillarme, Valerie Pichon, Thierry Fournier, Nathalie Delaunay
    Abstract:

    Abstract For the first time, the human Chorionic Gonadotropin (hCG) hormone at the intact level was characterized by reversed phase liquid chromatography (RPLC) coupled with high resolution mass spectrometry (HRMS). This heterodimeric protein is specific to human pregnancy, consists in an α and a β subunit, so-called hCGα and hCGβ, respectively, and has 8 glycosylation sites leading to a high number of isoforMS. First, the LC method was optimized to separate the largest number of isoforMS and also to facilitate the MS Ionization process and data treatment. The initial mobile phase composition, slope of the gradient, and column temperature were appropriately selected to maximize the number of separated isoforMS. Moreover, the MS detection parameters were adjusted to i) promote the efficient transfer of the heaviest ions, ii) avoid or limit the fragmentation of the ions and iii) improve the sensitivity. The repeatability of the final method in terMS of retention times and peak areas was assessed. The method was next used to characterize two hCG-based drugs: Ovitrelle® (a recombinant hCG, r-hCG) and Pregnyl® (hCG isolated from urine of pregnant women, u-hCG). After the deconvolution step, the analytical method did not allow to observe the isoforMS of the hCGβ. This may be due to its dramatic higher heterogeneity induced by its 6 glycosylation sites and a lack of Ionization in the MS source. Nevertheless, the results revealed the presence of more than 30 hCGα isoforMS, which differ by their number and their nature in the two drugs. Then, the molecular weights of the N-glycans already described in the literature for hCG were compiled in a database to identify the hCGα glycoforMS by mass matching. This strategy was successfully applied for the identification of five glycoforMS for both r-hCG and u-hCG. This work demonstrates for the first time the potential of RPLC-HRMS for the identification of the intact hCGα glycoforMS.

Damia Barcelo - One of the best experts on this subject based on the ideXlab platform.

  • how recent innovations in gas chromatography mass spectrometry have improved pesticide residue determination an alternative technique to be in your radar
    Trends in Analytical Chemistry, 2020
    Co-Authors: Yolanda Pico, Ahmed H Alfarhan, Damia Barcelo
    Abstract:

    Abstract Recent advances in gas chromatography-mass spectrometry (GC-MS) (Ionization sources at atmospheric pressure, fast GC, GCxGC, high resolution mass spectrometry, etc.) have significantly improved the capabilities of this technique, traditionally used to determine pesticides. Although liquid chromatography mass spectrometry (LC-MS/MS) is nowadays preferred, pyrethroids and organochlorine pesticides are more sensitive by GC-MS and a significant number of other pesticides work well by both techniques. Here, we critically review the development, instrumentation, approaches and applications of GC-MS, focusing on the analysis of pesticide residues published between 2000 and 2019 along with outstanding pioneer contributions, with special emphasis on those published after 2010. This review attempts to fill a void of information on the state-of-art of GC-MS for pesticide residue determination, describing the pros and cons of the different approaches, and the main applications.

Graham R Cooks - One of the best experts on this subject based on the ideXlab platform.

  • desorption electrospray Ionization mass spectrometry for lipid characterization and biological tissue imaging
    Biochimica et Biophysica Acta, 2011
    Co-Authors: Livia S Eberlin, C R Ferreira, Allison L Dill, Graham R Cooks
    Abstract:

    Desorption electrospray Ionization mass spectrometry (DESI-MS) imaging of biological samples allows untargeted analysis and structural characterization of lipids ionized from the near-surface region of a sample under ambient conditions. DESI is a powerful and sensitive MS Ionization method for 2D and 3D imaging of lipids from direct and unmodified complex biological samples. This review describes the strengths and limitations of DESI-MS for lipid characterization and imaging together with the technical workflow and a survey of applications. Included are discussions of lipid mapping and biomarker discovery as well as a perspective on the future of DESI imaging.